Earlier studies from this laboratory showed that tissues in or near the pharynx secrete in man a lipase that acts in the stomach, at pH, 5.4, to hydrolyze triacylglycerol to di- and monoacylglycerols and fatty acids, and that this is the first step in the digestion of dietary fat. The products formed are amphiphilic, and thereby facilitate emulsification of triacylglycerol before it leaves the stomach. The objectives of this project are (1) isolate and purify pharyngeal lipase from tissues of rats and other species, and from pharyngeal secretions of man. (2) Characterize the action of pharyngeal lipase. (3) Study the regulation and mode of secretion of pharyngeal lipase. (4) Determine role of pharyngeal lipase in fat digestion in normal and diseased states, in both infants and adults.